Optical aberration compensator

ABSTRACT

A color image is generated as a composite of images from different image modulators, each modulating a different color, and chromatic aberration of at least one optical element in the associated optical system is compensated by scaling or shifting images from different image modulators differently.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The instant application is a continuation of U.S. applicationSer. No. 09/995,034 filed on Nov. 27, 2001, issuing as U.S. Pat. No.6,678,095, which claims the benefit of prior U.S. ProvisionalApplication Serial No. 60/253,233 filed on Nov. 27, 2000, prior U.S.Provisional Application Serial No. 60/269,114 filed on Feb. 15, 2001,and prior U.S. Provisional Application Serial No. 60/298,259 filed onJun. 12, 2001. All of the above-identified applications are incorporatedherein by reference in their entirety.

BRIEF DESCRIPTION OF DRAWINGS

[0002] In the accompanying drawings:

[0003]FIG. 1 illustrates an anamorphic optical system incorporatingcorrector optics and a pair of prisms;

[0004]FIG. 2 illustrates an embodiment of an anamorphic optical systemincorporating a cylindrical corrector;

[0005]FIG. 3 illustrates an embodiment of an anamorphic optical systemincorporating a cylindrical window corrector;

[0006]FIG. 4a illustrates an isometric view of a variable corrector;

[0007]FIG. 4b illustrates an isometric view of a variable correctortogether with an associated adjusting mechanism;

[0008]FIG. 5 illustrates a cross-section of a variable cylindricalcorrector;

[0009]FIG. 6 illustrates a clamp mechanism that can be used inaccordance with the embodiments of FIGS. 5 and 7;

[0010]FIG. 7 illustrates an embodiment of an anamorphic optical systemwherein corrector optics are incorporated in the prisms;

[0011]FIG. 8 illustrates an embodiment of a prism at least partiallyfilled with optical fluid, that compensates for variations in pressureor temperature;

[0012]FIG. 9 illustrates an embodiment of an anamorphic opticalsubsystem comprising three prisms;

[0013]FIG. 10 illustrates a projection imaging system adapted tocompensate for chromatic aberration by an anamorphic optical subsystem;

[0014]FIGS. 11a, 12 a and 13 a illustrate red, blue and green imagecomponents without compensation for chromatic aberration;

[0015]FIGS. 11b, 12 b and 13 b illustrate red, blue and green imagecomponents with compensation for chromatic aberration;

[0016]FIG. 14a illustrates a resulting image from the image componentsshown in FIGS. 11a, 12 a and 13 a;

[0017]FIG. 14b illustrates a resulting image from the image componentsshown in FIGS. 11b, 12 b and 13 b; and

[0018]FIG. 15 illustrates a second embodiment of a projection imagingsystem adapted to compensate for chromatic aberration by an anamorphicoptical subsystem.

DETAILED DESCRIPTION

[0019] An anamorphic optical system provides for differentmagnifications in different orthogonal directions normal to an opticaxis. Anamorphic lenses are most commonly used in the film industry toeither compress a wide-field image into a more square frame duringfilming or to decompress the developed film frame upon projection.Recently the home theater industry has similarly started to useanamorphic lenses to reformat the more square, 4:3 aspect ratio of thecommon front-projected image into a 16:9 aspect ratio to take advantageof anamorphically compressed DVD movies. By using all the pixels of the4:3 projector to show a 16:9 image, the image is both brighter andhigher resolution than that provided by the conventional letter boxformat where pixels at the top and bottom of the image are unused.

[0020] A first known anamorphic optical system combines spherical andcylindrical lenses to preferentially magnify a beam or image in onedirection. A second known anamorphic optical system uses a pair ofprisms to provide this magnification while minimizing the amount ofnecessary deviation to the light path. These known systems, particularlythe latter, exhibit anamorphic aberrations that are compounded if thefocal length of the incident light varies, as may occur in home theaterprojection applications. A third known system using off-axis mirrorsgenerally exhibits fewer aberrations, but generally requires relativelylarge mirrors which increase the size of the resulting system. Theseknown anamorphic optical system are each an example of what is referredto hereinbelow as an anamorphic optical subsystem.

[0021] Anamorphic optical systems are known to operate best in an afocal arrangement. There is sufficient prior art describing the use ofcollimation optics before and/or after the anamorphic optical system toprovide this condition. This collimation condition is approximated insome applications such as home theater environments since the projectedimage is substantially distant from the projection lens and the apertureof the projection lens is very small relative to this distance. However,even slight deviations from ideal collimation will create astigmaticfocus aberrations in the image.

[0022] Referring to FIG. 1, an anamorphic optical system 10 comprises ananamorphic optical subsystem 12 in series with corrector optics 14. Forexample, an anamorphic optical subsystem 12 may comprise a prismaticanamorphic optical subsystem 12′ comprising at least one prism. As knownby one of ordinary skill in the art, depending upon its orientationrelative to a beam of incident light 16, a prism 18, can either expandor compress the size of a beam or image. Whereas a single prism 18provides for both anamorphic magnification and redirection of the beamof incident light 16, a pair of prisms 18 may be adapted to provide foranamorphic magnification without redirecting the beam of incident light16.

[0023] More particularly, the pair of prisms 18 comprise a first prism18.1 and a second prism 18.2. The first prism 18.1 comprises first 19.1and second 19.2 surfaces, wherein a first plane 19.1′ underlying thefirst surface 19.1 intersects with a second plane 19.2′ underlying thesecond surface 19.2 at a first apex 21.1. The first prism 18.1 furthercomprises a first base boundary 23.1, wherein the first surface 19.1comprises a first edge 25.1 that is distal to the first apex 21.1, thesecond surface 19.2 comprises a second edge 25.2 that is distal to thefirst apex 21.1, and the first base boundary 23.1 extends between thefirst edge 25.1 and the second edge 25.2. The first prism 18.1 furthercomprises at least one optical medium 27 between the first 19.1 andsecond 19.2 surfaces.

[0024] Similarly, the second prism 18.2 comprises third 19.3 and fourth19.4 surfaces, wherein a third plane 19.3′ underlying the third surface19.3 intersects with a fourth plane 19.4′ underlying the fourth surface19.4 at a second apex 21.2. The second prism 18.2 further comprises asecond base boundary 23.2, wherein the third surface 19.3 comprises athird edge 25.3 that is distal to the second apex 21.2, the fourthsurface 19.4 comprises a fourth edge 25.4 that is distal to the secondapex 21.2, and the second base boundary 23.2 extends between the thirdedge 25.3 and the fourth edge 25.4. The second prism 18.2 furthercomprises at least one optical medium 27 between the third 19.3 andfourth 19.4 surfaces.

[0025] The pair of prisms 18.1, 18.2 are adapted to provide foranamorphic magnification by arranging the first 18.1 and second 18.2prisms in a complementary relationship, so that the first apex 21.1 isaligned with the second base boundary 23.2 and the first base boundary23.1 is aligned with the second apex 21.2. The first 18.1 and second18.2 prism in combination generate at least one aberration in the beamof light passing therethrough.

[0026] The corrector optics 14 are adapted to aberrate the incidentlight 16 in a manner that at least partially compensates for at leastone aberration caused by anamorphic optical subsystem 12, so as toreduce the amount of aberration in the beam of exit light 20 caused bythe anamorphic optical system 10. For example, with the incident light16 entering the anamorphic optical subsystem 12 after passing throughthe corrector optics 14, the corrector optics 14 acts to pre-aberratethe light entering the anamorphic optical subsystem 12 so as to reducethe resulting net aberrations in the exit light 20. Generally, thecorrector optics 14 may be placed anywhere in the optical path, eitherahead of or after the anamorphic optical subsystem 12. However, if theincident light 16 exhibits angular field properties rather than beingunidirectional, the arrangement illustrated in FIG. 1 would generallyrequire smaller corrector optics 14 than if the corrector optics 14 werelocated after the anamorphic optical subsystem 12 where the lightexiting therefrom could be significantly diverged.

[0027] The anamorphic optical subsystem 12 is designed in accordancewith known principles to generally produce a desired anamorphicmagnification of the incident light 16. Whereas the corrector optics 14may be adapted to other types of anamorphic optical subsystems 12, aprismatic anamorphic optical subsystem 12′ is advantageous in notsignificantly changing the direction of incident light 16, and in beingrelatively simple to manufacture.

[0028] The corrector optics 14 may be constructed in accordance with anyof a variety of different embodiments, as described hereinbelow. Theselection of a particular embodiment is dependent upon the desiredcharacteristics of the anamorphic optical system 10. The correctoroptics 14 is also adapted to provide a slight focus change (opticalpower) that is different in the direction of anamorphic magnificationthan it is in an orthogonal direction, so as to compensate for anasymmetric, somewhat astigmatic focus shift that is different in thesetwo directions, which is generally characteristic of the aberrations ofanamorphic optical subsystems 12. By effectively applying a cylindricallens, or a functionally similar element, as a corrective element incombination with a slight spherical (uniform) power to the incidentlight 16 (such as through the focusing of a projection lens), thisresidual aberration can be substantially corrected so that the imagecomes into focus in both directions on the same image surface.

[0029] Referring to FIG. 2, the corrector optics 14 comprises acylindrical corrector 22, the curvature of which is exaggerated in FIG.2 for purposes of illustration. For example, an anamorphic compressionof 25% of an image at a distance of ten (10) meters from a projectionlens required a plano-convex cylindrical corrector 22 having a twelve(12) meter radius to bring the image into focus. A cylindrical lens inthe orthogonal direction would require a concave surface. The anamorphicoptical system 10 with a cylindrical corrector 22—and also generally forother corrector optics 14 arrangements—benefits from a specific focallength of the incident light 16 to provide a given focal length of theexit light 20 with best focus. Such parameters are readily generatedthrough the use of conventional optical design algorithms known to thoseof ordinary skill in the art. The curvature of the cylindrical corrector22 depends upon the nature of the associated aberration to be corrected.Moreover, the associated radius of curvature is not necessarilyconstant, which is generally true herein when any reference is made to acylindrical curvature or to a cylindrical lens.

[0030] Referring to FIG. 3, for systems where it is desirable to have anadjustable focal length of the exit light 20 it is also preferable toalter the focal length of the corrector optics 14 in combination with analteration of the focal length of the incident light 16. The generallylong distance of the corrector focal length can be exploited byintroducing a thin optical window, for example, made of plastic,initially oriented as shown in FIG. 3, and bent into a radius by forcesapplied at the edges so as to form a cylindrical window corrector 24.When a material is bent, the two surfaces do not maintain a perfectparallel relationship and the respective radii of the surfaces thereforebecome slightly different, so as to induce a slight optical power. Forexample, a 0.5 millimeter acrylic sheet was sufficient to correct theaberrations present in an image that was anamorphically compressed by25% using a prismatic anamorphic optical subsystem comprising a prismpair, with a projector-to-screen distance of approximately three (3)meters. Changing the distance to the screen (the focal length of exitlight 20), can be readily accommodated by altering the amount ofcurvature on the window in combination with a minor focus adjustment ofthe projector lens. The bending is preferably performed in the axisorthogonal to the compression axis (rotated ninety degrees around theoptic axis 29 from the illustrated orientation), which suggests that thebent thin window becomes relatively thinner in the center than at itsedges with respect to the incident light 16, resulting in a negativepower that is prescribed in the orthogonal direction as per the optionalplano-concave (negative) corrector of the embodiment illustrated inFIG. 1. Accordingly, the curvature of the cylindrical window corrector24 is substantially transverse to a plane 31 of anamorphic magnificationof the prismatic anamorphic optical subsystem 12′.

[0031] Referring to FIGS. 4a and 4 b, the corrector optics 14 maycomprise a variable corrector 26 comprising first 28 and second 30anamorphic elements, each comprising any single subelement or group ofsubelements exhibiting anamorphic power. Each first 28 and second 30anamorphic element has an associated direction 32.1, 32.2 of anamorphicpower, and the first 28 and second 30 anamorphic elements are mounted inan assembly with a mechanism by which the first 28 and second 30anamorphic elements can be rotated relative to one another, therebyrotating the corresponding directions 32.1, 32.2 of anamorphic powerrelative to one another. For example, as illustrated in FIG. 4b, thefirst 28 and second 30 anamorphic elements can be mounted in respectivewheel structures 34.1, 34.2 of a counter-rotating mechanism 35substantially aligned with and parallel to one another, and which areadapted to be rotated with respect to one another, wherein therespective directions 32.1, 32.2 of anamorphic power are each orientedparallel to a common plane. For example, facing surfaces 36.1, 36.2 ofthe wheel structures 34.1, 34.2 may incorporate teeth, for example gearteeth, particularly conical gear teeth, or a friction surface thatengage with mating teeth or a mating surface operatively connected to anadjusting knob 38, whereby the variable corrector 26 is adjusted byrotating the adjusting knob 38, which symmetrically counter-rotates theassociated wheel structures 34.1, 34.2, thereby counter-rotating thedirection 32.1, 32.2 of anamorphic power of the respective first 28 andsecond 30 anamorphic elements. The relative amount of anamorphicmagnification in orthogonal directions is responsive to thecounter-rotation angle □ of the first 28 and second 30 anamorphicelements. The variable corrector 26 provides for correcting prism errorsover a wide range of focal lengths of the incident light 16. Moreover,the first 28 and second 30 anamorphic elements may advantageouslycomprise conventional, stress-free elements such as cylindrical lenses.The cylindrical power of the first 28 and second 30 anamorphic elementscan be determined by optimizing the optical design over the desiredrange of desired exit light 20 focal lengths in combination with avariable focal change of the incident light 16.

[0032] Referring to FIG. 5, the corrector optics 14 may comprise avariable cylindrical corrector 40 comprising a cavity 42 between twooptical surfaces 44, wherein the optical surfaces 44 are deformed, forexample, by applying a clamping force 46 along opposing edges 48 of theoptical surfaces 44, wherein the amount of resulting optical power ofthe variable cylindrical corrector 22 is responsive to the amount ofclamping force 46. The cavity 76 is at least partially filled with anoptical fluid 50, for example, an optical liquid such as mineral oil,that in one embodiment reacts against the optical surfaces 44 responsiveto the clamping forces 46 thereby causing at least one optical surface44 to deform into a cylindrical shape. Different optical surfaces 44having respectively different thicknesses deform by different amountsthereby providing for different amounts of relative optical power, sothat with one surface relatively thick, and the other relatively thin, asubstantially plano-convex lens is formed responsive to the clamping orpressurization. For example, first 52 and second 54 glass substrates maybe bonded to one another along a perimeter 56, for example, by a layerof flexible silicone along the perimeter 56. In another embodiment, thedeformation of the first glass substrate 52 may be assisted orcontrolled by fulcrums 57 between the first 52 and second 54 glasssubstrates at each end thereof.

[0033] Referring to FIG. 6, the clamping force 46 may be generated by atleast one clamp mechanism 59 operatively coupled to either both opposingedges 48, or to one of the opposing edges 48 provided that the otheropposing edge 48 is retained by some other means, e.g. a frame, clip orbond. For example, the clamp mechanism 59 illustrated in FIG. 6comprises a push bar 61 that distributes the clamping force 46 acrossthe opposing edge 48 being clamped. The clamp mechanism 57 furthercomprises a cam 63 that engages with a follower surface 65 in or on thepushbar 59, and that is rotated by a knob 67. As the knob 67 is rotated,the cam 63 engages the follower surface 65, which moves the push bar 61against the opposing edge 48 of the first glass substrate 52 whichgenerates an adjustable clamping force 46 thereon which is reacted by aframe (not illustrated) operatively connected to the cam 63 and to thesecond glass substrate 54. Accordingly, the curvature of the first glasssubstrate 52 is responsive to the clamping force 46, which in turn isresponsive to the position of the cam 63.

[0034] Alternately, the optical surfaces 44 may be deformed by eitherpressurizing the optical fluid 50 in the cavity 42 to form at least oneconvex surface, or by evacuating the cavity 42 to form at least oneconcave surface. If the first 52 and second 54 glass substrates aresubstantially longer than they are wide, then responsive topressurization, the deformation will be substantially greater across thewidth 58 than across the length of the deforming substrate. The variablecylindrical corrector 22 may be further provided with additionalstructure to preferentially stiffen the substrates along one directionso as to prevent bending in that direction.

[0035] Referring to FIG. 7, a variable cylindrical corrector 40.1 may beincorporated into at least one surface of a prism 59, wherein thecorrector optics 14 are incorporated in the associated prismaticanamorphic optical subsystem 12′ of the associated anamorphic opticalsystem 10. Rather than using a conventional solid prism, at least oneprism 59 of an anamorphic optical system 10 may, for example, comprise apair of flat windows 60, for example, of glass, bonded to a prismaticshell or frame 62 and at least partially filled with an optical liquid64. At least one surface 66, particularly the edge thereof, of such aprism 59 may include a flexible seal 68 and a clamp mechanism 59 forapplying an edge pressure so as to deform the surface 66, therebyproviding cylindrical optical power. This obviates the need for separatecorrector optics 14. Flat windows 60 that are intended to remain flatmay, for example, be bonded to the prismatic shell or frame 62 with arelatively rigid adhesive, for example, with epoxy. The resultingrelatively thick prisms 59, 18 can be readily adapted with ports 72 forat least partially filling the prisms 59 with optical liquid 64, so asto provide the variable correction feature and for reducing the cost ofthe associated anamorphic optical subsystem 12. Moreover, because theliquid volume of the prism 59 incorporating a variable cylindricalcorrector 40.1 is substantially greater than that of a relatively thin,separate variable cylindrical corrector 40, there is less of arestriction to the local flow of fluid therein as the edge pressure isapplied to the associated optical surfaces 44, resulting in a fastersettling response of the system to a pressure setting. The surfaces 66of the prismatic anamorphic optical subsystem 12″ that preferablyinclude variable power may be determined through optimization of theanamorphic optical system 10 through known optical design algorithms.

[0036] The at least one prism 59 at least partially filled with opticalfluid 50, described hereinabove, provides a cost-effective way offabricating relatively high quality, relatively large prisms. Relativelyhigh quality optical glass sheets are readily available at low cost,even with antireflection coatings pre-applied to the external surfaces.However, changes in atmospheric pressure and temperature can cause adifferential pressure between the inside and outside of the prism that,under extreme conditions, can stress the structure thereof and, even inminor cases, can warp the optical surfaces 44 causing aberrations in theassociated image.

[0037] One way this problem can be mitigated is by partially filling theprism 59 with optical fluid 50, thereby leaving a volume—e.g. comprisingair or some other gas, e.g. nitrogen or an inert gas—within the prism 59so as to provide for the change in volume of the optical fluid 50without causing excessive variations in pressure that could otherwiseadversely distort at least one optical surface 44 of the prism 59.Alternately, the prism 59 could incorporate a vessel, or a material,therein adapted to be substantially more compliant than the opticalsurfaces 44 of the prism 59 so as to provide similar compensation.

[0038] Alternately, referring to FIG. 8, this problem can be mitigatedby incorporating a flexible membrane 74, e.g. neoprene or VITON®, in oneend of the prism 59, e.g. part of a wall of the prism housing. Theflexible membrane 74 is impermeable to the optical fluid 50, and issubstantially more flexible than the optical surfaces 44, e.g. glassplates, yet not so flexible as to sag under the hydrostatic pressure ofthe fluid if the prism 59 is inverted. The prism 59 may optionallyfurther incorporate a relatively small cavity 76 proximate to a side ofthe flexible membrane 74 opposite to the optical fluid 50, that isvented to atmosphere through a relatively small orifice 78 that issufficiently small so as to dampen the effects of relatively rapidchanges to the pressure of the optical fluid 50, e.g. as caused byforces on the prism 59, e.g. from shipping and handling, butsufficiently large to enable the flexible membrane 74 to compensate forrelatively long term changes in pressure or temperature. It should beunderstood that the flexible membrane 74—with or without the cavity 76and orifice 78—could alternately be incorporated in a plug that sealsthe associated port 72 through which the prism 59 is at least partiallyfilled with optical fluid 50. For example, the plug could be adapted tothread into the prism 59, and could incorporate an external flange thatwould seal against a surface of the prism 59 with an O-ring.

[0039] Whereas the anamorphic optical system 10 of FIG. 7 is illustratedincorporating a clamp mechanism 59 for deforming at least one surface 66of at least one prism 59, it should be understood that the at least onesurface 66 could alternately be constructed with a single, fixedcylindrical face, and thereby provide satisfactory results for at leastsome applications. For example, in the common home theater projectionscenario, for a vertical compression (anamorphic magnification) ofapproximately 25%, the cylindrical curvature of the second surface 19.2of the first prism 18.1 was minus 6500 millimeters (concave with respectto the fluid, externally convex, as generally shown in FIG. 5) for aprojector to screen distance of 4.5 meters. In practice, this curvatureprovides sufficient quality for a range of projector to screen distancesbetween approximately 3 and 7 meters so as to substantially obviate theneed for variable focusing.

[0040] Accordingly a fixed cylindrical face was created by machining theappropriate curvature into the end plates 79 of the prismatic shell orframe 62 and then bonding—e.g. with an epoxy—and clamping the associatedoriginally flat window 60 to the curved surface. In this case, it isbeneficial for the stiffness of the flat window 60 to be sufficient tomaintain the cylindrical curvature over the entire surface, while alsobeing sufficiently flexible to form the curvature without undergoingfracture or other failure. In the case of a 6500 millimeter radius, a1.6 millimeter thick flat window 60 of glass sheet provided suitableproperties for a prism approximately 150 millimeters across the secondsurface 19.2.

[0041] Moreover, whereas the anamorphic optical system 10 of FIG. 7 isillustrated incorporating prisms 59 at least partially filled withoptical fluid 50, it should be understood that one or more prisms 59could alternately be solid, e.g. constructed of one or more materials,e.g. one material, e.g. optical glass.

[0042] Several problems that are typically associated with anamorphicoptical systems are barrel-shaped distortion under image compression,and pincushion distortion under expansion, each of which increases withthe amount of magnification. The combination of corrector optics 14 withan associated anamorphic optical subsystem 12 provides synergisticbenefits. For example, a cylindrical lens system may be used to expandthe horizontal direction of an image, creating pincushion distortion. Acorrected prismatic assembly may then be used to compress the verticaldirection of the image, increasing the overall relative magnificationbetween the horizontal and vertical directions.

[0043] The two assemblies may be independently or jointly corrected formost optical aberrations. However, the distortions of each assembly,being opposite in sign, are applied against each other to minimize thenet result.

[0044] The anamorphic optical system 10 described herein can be used ina variety of applications that would benefit from anamorphicmagnification with relatively reduced aberrations, for example,including, but not limited to, home theater projection or fortransforming a laser beam—for example, as generated by a diodelaser—from an elliptical to a circular cross-section.

[0045] As described hereinabove, a prism assembly may be used to stretchor compress one dimension of a projected image. However, without furthercompensation, there can be a residual lateral chromatic aberration inthe resulting image. This aberration may be reduced by pre-aberratingthe image prior to entering the prism assembly.

[0046] Depending on the angles and orientation of the prism 18.1, 18.2,certain characteristics in the resulting image, for example, thelinearity of the vertical compression, can be optimized, perhaps as atrade-off with respect to other characteristics. Moreover, referring toFIG. 9, the prismatic anamorphic optical subsystem 12′ may be adapted toincrease the anamorphic magnification by using three prisms, forexample, each filled with an optical fluid as illustrated in FIG. 8. Forexample, the prismatic anamorphic optical subsystem 12″ illustrated inFIG. 7 can be adapted with a third prism 18.3 before the first prism18.2, wherein the second surface 19.2 of the first prism 18.1 is adaptedto incorporate a curved refractive element as described hereinabove.

[0047] Referring to FIG. 10, in another embodiment of an anamorphicoptical system 10 that pre-aberrates the image, a projector 80 havingdedicated red, green and blue image component generators is used whereinthe size and position of the image of each component generator ismodified to produce this pre-aberration. The projector 80 comprises awhite light source 82, the light from which is distributed to respectivered 84, green 86, and blue 88 image modulators either by respective beamsplitters 90, 92 or mirror(s) 94, or by separate illumination of therespective image modulator 84, 86, 88. The particular colored light foreach respective image modulator 84, 86, 88 is either filtered before orwithin the respective image modulator 84, 86, 88. The respective coloredlight from the respective image modulators 84, 86, 88 is thenrecombined—for example, with associated mirror(s) 90′ and beam splitters92, 94′—and projected by projection optics 95, e.g. a projection lens,so as to form a beam of incident light 16 upon the corrector optics 14and anamorphic optical subsystem 12 as described hereinabove. It shouldbe understood that it is beneficial for the respective beam paths fromeach respective image modulator 84, 86, 88 to the projection optics 95tobe generally equidistant, notwithstanding that this condition is notillustrated literally in FIG. 8 as drawn.

[0048] In operation, for the anamorphic optical subsystem 12 comprisinga prismatic anamorphic optical subsystem 12′ oriented to as to introduceaberrations along the vertical axis (Z), each component image isvertically scaled and then vertically shifted by the respective one ormore image modulators 84, 86, 88 to compensate for the anamorphic lenslateral chromatic aberration. The vertical scaling (compression orexpansion) may be performed either with a dedicated anamorphic lens atthe component image modulator 84, 86, 88, or preferably, by prescalingthe electronic image using a readily available electronic scaling device96. The shifting of the respective image components of the respectivecolors may also be performed by electronically shifting the imagelocation vertically on the modulator by simply adjusting the verticalposition of the modulator.

[0049] If the respective image components of the respective colors arenot shifted and scaled—as is illustrated respectively in FIGS. 11a, 12 aand 13 a—then the corresponding image components in the composite imageare not properly aligned with one another, as is illustrated in FIG.14a. The respective image components in the composite image—illustratedin FIG. 14b—are properly aligned as a result of the above describedscaling applied to the individual image components—illustrated in FIGS.11b, 12 b and 13 b, wherein the blue image is not compressed, the redimage is vertically compressed, and the green image is verticallycompressed less than the red image, so that the integrated image in FIG.14b does not exhibit evidence of chromatic aberration.

[0050] Referring to FIG. 15, in a second embodiment, an electronicsignal 98.1, 98.2, 98.3 to each image component generator 100.1, 100.2,100.3 is modified by a respective scaler/positioner 102.1, 102.2, 102.3to achieve the proper result by altering the size and position of eachcomponent image on its respective image component generator 100.1,100.2, 100.3. The scaling and shifting of the respective imagecomponents is in accordance with the description hereinabove. If asingle modulator is used for all colors, then the component images foreach color are preferably compressed and shifted electronically. As analternative to vertical scaling symmetrically about the optical axis andshifting, each image may be scaled so that the compression is greater inone vertical location than another, thereby effectively compressing thecomponent image toward the vertical position of least chromaticaberration.

[0051] While specific embodiments have been described in detail, thosewith ordinary skill in the art will appreciate that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the invention, which is to be given thefull breadth of the appended claims, and any and all equivalentsthereof.

I claim:
 1. An optical system comprising: a. at least one opticalelement; b. at least one source of light; and c. at least one imagemodulator, wherein said at least one source of light generates acorresponding at least one beam of light, at least one of said at leastone beam of light is modulated by said at least one image modulator soas to form a corresponding modulated beam of light, said modulated beamof light is directed through said at least one optical element, at leastone said optical element causes a chromatic aberration of said modulatedbeam of light, and said at least one image modulator modulates said atleast one beam of light with an image signal that is adapted to scale orshift or both scale and shift said incident beam of light so as tocompensate for said chromatic aberration by said at least one saidoptical element.
 2. An optical system as recited in claim 1, whereinsaid image signal is adapted responsive to a color of said modulatedbeam of light.
 3. An optical system comprising: a. at least one opticalelement; and b. at least one image component generator, wherein said atleast one image component generator generates a corresponding modulatedbeam of light, said modulated beam of light is directed through said atleast one optical element, at least one said optical element causes achromatic aberration of said modulated beam of light, and a modulationof said modulated beam of light is adapted to scale or shift or bothscale and shift said modulated beam of light relative to anothermodulated beam of light generated by another of said at least one imagecomponent generator so as to compensate for said chromatic aberration bysaid at least one said optical element.
 4. An optical system as recitedin claim 3, wherein said modulation of said modulated beam of light isadapted responsive to a color associated with said modulated beam oflight.